Simultaneous visible and fluorescence endoscopic imaging

ABSTRACT

An endoscope apparatus includes a fiber optic cable with a proximal end and a distal end opposite the proximal end. The endoscope apparatus also includes a light source optically coupled to the proximal end of the fiber optic cable to emit visible light and excitation light into the fiber optic cable for output from the distal end. The light source is configured to emit both the visible light and the excitation light simultaneously, and a wavelength of the excitation light is outside a wavelength spectrum of the visible light. An image sensor coupled to the distal end of the fiber optic cable and positioned to receive a reflection of the visible light as reflected visible light.

TECHNICAL FIELD

This disclosure relates generally to endoscope imaging.

BACKGROUND INFORMATION

Endoscopy allows a physician to view organs and cavities internal to apatient using an insertable instrument. This is a valuable tool formaking diagnoses without needing to guess or perform exploratorysurgery. The insertable instruments, sometimes referred to as endoscopesor borescopes, have a portion, such as a tube, that is inserted into thepatient and positioned to be close to an organ or cavity of interest.

Endoscopes first came into existence in the early 1800's, and were usedprimarily for illuminating dark portions of the body (since opticalimaging was in its infancy). In the late 1950's, the first fiber opticendoscope capable of capturing an image was developed. A bundle of glassfibers was used to coherently transmit image light from the distal endof the endoscope to a camera. However, there were physical limits on theimage quality this seminal imaging endoscope was able to capture:namely, the number of fibers limited the resolution of the image, andthe fibers were prone to breaking.

Now endoscopes are capable of capturing high-resolution images, asendoscopes use various modern image processing techniques to provide thephysician with as natural a view as possible. However, sometimes it maybe desirable to see contrast between organs imaged. For instance, somecancers look very similar to surrounding healthy tissue.

BRIEF DESCRIPTION OF THE DRAWINGS

Non-limiting and non-exhaustive embodiments of the invention aredescribed with reference to the following figures, wherein likereference numerals refer to like parts throughout the various viewsunless otherwise specified. Not all instances of an element arenecessarily labeled so as not to clutter the drawings where appropriate.The drawings are not necessarily to scale, emphasis instead being placedupon illustrating the principles being described.

FIG. 1A is an illustration of an endoscope system, in accordance with anembodiment of the disclosure.

FIG. 1B shows an endoscope emission spectrum and a correspondingfluorescence emission spectrum, in accordance with an embodiment of thedisclosure.

FIG. 1C shows an endoscope emitting visible and excitation light,receiving a fluorescence emission spectrum, and forming a compositeimage on a screen, in accordance with an embodiment of the disclosure.

FIG. 2 illustrates an endoscopic light emitter, in accordance with anembodiment of the disclosure.

FIGS. 3A-3D illustrate a method of calculating a visible andfluorescence image, in accordance with an embodiment of the disclosure.

FIG. 4 illustrates a method of medical imaging, in accordance with anembodiment of the disclosure.

DETAILED DESCRIPTION

Embodiments of a system and method for simultaneous visible andfluorescent endoscopic imaging are described herein. In the followingdescription numerous specific details are set forth to provide athorough understanding of the embodiments. One skilled in the relevantart will recognize, however, that the techniques described herein can bepracticed without one or more of the specific details, or with othermethods, components, materials, etc. In other instances, well-knownstructures, materials, or operations are not shown or described indetail to avoid obscuring certain aspects.

Reference throughout this specification to “one embodiment” or “anembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the present invention. Thus, theappearances of the phrases “in one embodiment” or “in an embodiment” invarious places throughout this specification are not necessarily allreferring to the same embodiment. Furthermore, the particular features,structures, or characteristics may be combined in any suitable manner inone or more embodiments.

Endoscopes are devices physicians use to view inside of patients withoutthe need to perform exploratory surgery. In general, endoscopes areimaging devices with insertion tubes that are inserted into a patientthrough small incisions. The imaging device provides views from a tip(“distal end”) of the insertion tube and displays the view, for example,on a monitor for the physician. The distal end may be opposite thehand-held portion (“proximal end”) of the endoscope. The imaging systemmay provide a view of an area of interest to the viewer. The color of anobject imaged depends on the spectrum of the illumination light source,as well as the object's own spectral reflectance.

Indocyanine Green (ICG) is a dye that bind to proteins in the bloodplasma. When pumped with 805 nm light, ICG fluoresces with a peakwavelength at 830 nm. ICG can be injected into the bloodstream, andduring surgery, the ICG fluorescence can be imaged to show bloodperfusion and vasculature. In endoscopic surgery, the surgeon inserts anendoscope (with a camera and illumination source at the distal end ofthe endoscope) to image the surgical area of interest in real-time. Thisdisclosure may help solve the problem of obtaining a fluorescence imageto show the spatial distribution of the ICG, at the same time asobtaining a regular visible reflectance image, in real-time. The ICGimage may provide contrast information that a surgeon can use to bettertell the difference between various bodily structures.

This disclosure provides embodiments of an endoscope that may have twodiscrete laser sources at the proximal end, and a camera at the distalend (the end inserted into the surgical region). A fiber optic cable mayoptically transmit light from the discrete sources at the proximal endto the distal end. The disclosure may also include a connection from theendoscope to a computer (either internal or external to the endoscope),and the endoscope system includes software that processes the dataoutput from the endoscope image sensor and sends the data to a computermonitor display. The endoscope image sensor may employ a conventionalBayer filter pattern, such that each pixel records an image chargecorresponding to red, green, or blue light. On top of the Bayer filtermay be a notch filter.

The two discrete laser sources may be an 805 nm laser and a visiblewavelength laser. The notch filter may block almost all light at 805 nmwavelength but let light at other wavelengths through. Both the 805 nmlaser (the “excitation” laser) and the visible wavelength laser operatesimultaneously. The 805 nm laser may cause the ICG dye in the surgicalarea of interest to fluoresce around 830 nm, and the visible wavelengthlaser is reflected by the organs in the surgical area. Photons of threewavelength ranges (visible, 805 nm, and 830 nm) may impinge on thecamera, but almost all the 805 nm photons are blocked by the notchfilter. The three color pixels, red, green, and blue, each havedifferent quantum efficiencies for the three different wavelengthranges. Thus, the responses by the red, green, and blue pixels may beindependent linear combinations of the number of photons at each of thethree wavelengths of light. The values recorded by the red, green, andblue pixels are sent to the processor, and the software package on theprocessor/computer uses regularized inversion to computationallydetermine (from neighboring red, green, and blue pixel values) what theintensity values are for the fluorescent photons and the visiblereflected photons. The software may employ knowledge of the visiblelaser wavelength to convert the recorded red, green, and blue pixelintensity values to image data with the highest possible signal-to-noiseratio. The intensity values for the fluorescent photons and the visiblereflected photons are sent to the display, which may display a black andwhite image for the visible reflectance intensity values (the red,green, and blue pixels of the display are equally scaled by the visiblereflectance intensity), and a green overlay for the fluorescenceintensity values (a value proportional to the fluorescence intensity maybe added to the value for the green display pixel). However, in otherembodiments, a full color image may be formed with a fluorescenceoverlay of a color not commonly encountered in the human body (e.g.,florescent orange).

One advantage of the present disclosure is that no additional hardware(such as extra cameras, beam splitters, or image sensors) is needed torecord images at two different wavelengths. A camera and image sensorwith a Bayer filter can be used. The frame rate of the camera ismaintained, and the recorded images at the two different wavelengths areautomatically registered to each other.

It is worth noting different fluorophore and excitation laserwavelengths may be used. Moreover an image sensor with a fourth colorpixel (such as a near-infrared pixel), which causes there to be fourequations in the software algorithm, but the same regularized inversionmatrix can be used. Additionally, there may be multiple cameras in theendoscope (for example, for stereo imaging), but each camera mayseparately have the functionality of simultaneous fluorescence andvisible imaging.

FIG. 1A is an illustration of an endoscope system 100, in accordancewith an embodiment of the disclosure. Endoscope system 100 includes body102, fiber optic cable 104, light source 112, controller 108, computersystem 114 (including processor 110, data input/output 116, and powerinput 118), and image sensor 121.

Endoscope system 100 includes a proximal end (hand held), and a distalend (end of fiber optic cable 104 opposite the proximal end). Lightsource 112 is optically coupled to the proximal end of the fiber opticcable 104 to emit visible light 125 and excitation light 127 into fiberoptic cable 104 for output from the distal end. Light source 112 isconfigured to emit both visible light 125 and excitation light 127simultaneously, and the wavelength of the excitation light 127 isoutside the wavelength spectrum of the visible light 125 (see e.g., FIG.1B). Image sensor 121 is coupled to the distal end of fiber optic cable104 and positioned to receive a reflection of visible light 125 asreflected visible light. A filter is disposed over image sensor 121, andthe filter blocks a majority of excitation light 127 from reaching imagesensor 121 while passing a majority of the reflected visible light 125and fluorescent light to the image sensor 121.

FIG. 1B shows a visible light endoscope emission spectrum 125, anexcitation light emission spectrum 127, and a corresponding fluorescenceemission spectrum 129, in accordance with an embodiment of thedisclosure. In the depicted embodiment, visible spectrum 125 isillustrated as a single wavelength spectrum (or small range ofwavelengths); however, in other embodiments visible spectrum 125 mayhave other emission profiles. As shown the endoscope emits an excitationlight spectrum 127 which may be at ˜805 nm or another wavelength. In oneembodiment excitation light 127 may be higher energy than visible light125 such as ultraviolet light, depending on the dye used to create theflorescence spectrum. In some embodiments the wavelength of excitationlight 127 is outside a wavelength spectrum of the visible light 125. Asdepicted, in response to emitting excitation light 127 with the lightsource, image sensor 121 receives fluorescence light 129contemporaneously with the reflected visible light. Fluorescence light129 has a longer wavelength than excitation light 127. In oneembodiment, fluorescence light 129 includes ˜830 nm light; but in otherembodiments, fluorescence light 129 may be any light with lower energythan excitation light 127. It is worth noting that while in the depictedembodiment excitation light 127 and fluorescence light 129 arerelatively monochromatic, in other embodiments the emission profiles ofthese light sources may be wider so that they include a plurality ofwavelengths of light (and may even include a plurality of emissionpeaks).

FIG. 1C shows endoscope system 100 emitting visible and excitationlight, receiving a fluorescence emission spectrum, and forming compositeimage 151 on a screen, in accordance with an embodiment of thedisclosure. In the depicted embodiment, endoscope 100 is simultaneouslyemitting both visible and excitation light out of the distal end offiber optic cable 104. The visible and excitation light hits an organ(depicted here as lungs). The lungs have been injected or coated with afluorescent dye (e.g., molecules, semiconductor particles, etc.). Whenthe excitation light reaches the lungs the dye emits fluorescence light.The reflected visible light and fluorescence light is simultaneouslyreceived by image sensor 121, while a notch filter may be used to blockthe excitation spectrum from being absorbed by image sensor 121 in anysignificant quantity.

In the depicted embodiment, the reflected visible light and thefluorescence light form combined image data in image sensor 121. Thecombined image data may be separated in real time by a processing unit(disposed here in endoscope 100) into visible image data andfluorescence image data. In the depicted embodiment, the visible imagedata is commensurate (e.g., roughly proportional) to the reflectedvisible light received by image sensor 121 and the fluorescence imagedata is commensurate to the fluorescence light received by image sensor121. In one embodiment, separating the combined image data into visibleimage data and fluorescence image data includes separating the combinedimage data into red image data corresponding to red photocharge receivedby image sensor 121, green image data corresponding to green photochargereceived by image sensor 121, blue image data corresponding to bluephotocharge received by image sensor 121, and florescence image datacorresponding to fluorescence photocharge received by image sensor 121.The red image data, the green image data, and the blue image datacomprise the visible image data.

Also shown is converting the visible image data and the fluorescenceimage data into composite image 151. As depicted, the visible image dataand the fluorescence image data are displayed simultaneously to producecomposite image 151. Composite image 151 includes visible image 153(dashed line background) and fluorescence image 155 (solid lineforeground), where the fluorescence image is overlaid on visible image153. As previously described, visible image 153 may be black and whiteor color, and fluorescence image 155 may be green (or the like) overlaidon visible image 153.

FIG. 2 illustrates an endoscopic light emitter 200 (including lightsource 212), in accordance with an embodiment of the disclosure. Asshown the visible light is emitted from one or more visible lasersources 231, and the excitation light is emitted from the one or moreexcitation laser sources 239. The wavelength of the excitation light islonger than the wavelength spectrum of the visible light. The one ormore visible laser sources 231 and the one or more excitation lasersources 239 may be a single laser diode capable of emitting a pluralityof wavelengths, or may be multiple independent laser sources eachemitting a different wavelength of light. As depicted, light source 212may be optically coupled to fiber optic cable 204 to direct the visiblelight and the excitation light into a proximal end of fiber optic cable204. Thus the light is transmitted into fiber optic cable 204, and thelight is totally internally reflected within fiber optic cable 204 untilit reaches the distal end where it is emitted.

As illustrated, controller 208 is coupled to light source 212 toregulate the output of light source 212. For instance, the controller208 may be part of the processor system or may be a stand-alonecontroller to control the output of light source 212. In one embodiment,controller 208 may independently control the intensity of individuallaser sources to balance the amount of excitation light and visibleimage light emitted. In one embodiment, light source 212 may have anynumber of light sources including lasers and/or light emitting diodes.Further, while the lasers depicted in FIG. 2 emit relativelymonochromatic light (e.g., light with a bandwidth of less than 1 nm), inother embodiments, the bandwidth(s) of light source 212 may be larger(on the order of 5 nm or more). In some embodiments, fiber optic cable204 may include cladding to promote total internal reflection (e.g., thecladding may include a reflective metal, or a material with a lowerindex of refraction than the bulk of fiber optic cable 204), or containmultiple fibers.

FIGS. 3A-3D illustrate a method of calculating a visible andfluorescence image, in accordance with an embodiment of the disclosure.One of ordinary skill in the art will appreciate that all portions ofthe method depicted may occur in a processor/controller coupled to, orincluded in, the endoscope. Moreover the endoscope may communicate to alocal or remote processor via wireless or wired communication. In someembodiments, the processor/controller may be a distributed system (forexample in embodiments where a lot of data needs to be processed, e.g.,high definition video). It is appreciated that the embodiments depictedillustrate a situation where excitation light is 805 nm, and florescencelight is 830 nm, but in other embodiments, other wavelengths/dyes may beused.

FIG. 3A shows part of a method to calculate visible and fluorescenceimages from an endoscope. As illustrated, an image sensor generatesphotocharge in its pixels in response to receiving visible (red, green,and blue light), fluorescence light, and a relatively small quantity ofexcitation light. A processor coupled to the image sensor then separatesthe photocharge generated into the visible and florescence signal. Thisis achieved by using known parameters of the image sensor/endoscopesystem to solve a system of algebraic equations. For example, thevarious components that make up the red photocharge are known andinclude X₁ (photons absorbed at 830 nm) multiplied by QE₈₃₀ (the quantumefficiency of the image sensor at 830 nm—the fluorescence emissionwavelength) and T_(830,notch) (the transmission of 830 nm light throughthe notch filter). This term is then added to Y₁ (visible photonsabsorbed) multiplied by QE_(visible) (the quantum efficiency of theimage sensor in the visible wavelength) and T_(visible,notch)(transmission of visible light through the notch filter). This term isthen added to Z₁ (excitation photons absorbed) multiplied by QE₈₀₅ (thequantum efficiency of the image sensor in the excitation wavelength) andT_(805,notch) (the transmission of excitation light through the notchfilter). One of skill in the art will appreciate that this excitationterm is ˜0 since almost no excitation light will make it through thenotch filter. These terms are then added to the noise (N₁) of the imagesensor. As shown, similar equations are set up for green photocharge(P_(g)) and blue photocharge (P_(b)). The depicted system of equationsallow the visible (Y) and fluorescence (X) image signals to be solvedfor and yield the visible and fluorescence images.

FIG. 3B shows solving the system of equations to obtain the visible andfluorescence signals. FIG. 3B also introduces the concept ofregularization in order to stabilize both the matrix and ultimately thevisible and florescence images generated. In general, the mathematicaloperations need to solve for the visible and fluorescence images mayintroduce unstable conditions in certain situations (e.g., divide byzero, or other very small denominator, as a result of a readout glitchin the image sensor or the like). This may cause image distortion.Accordingly, the system may regularize the output by estimating valuesfor X, Y, and Z. In the depicted embodiment, Γ=αI, where I is theidentity matrix and a is a regularization constant. X, Y, and Z areestimated with L2 regularization such that:Q^(L)=(Q^(T)Q+Γ^(T)Γ)⁻¹Q^(T), and thus {circumflex over (X)}=Q^(L)P.

FIG. 3C depicts the mathematical operations to calculate the variance ofthe photocharge in the image sensor (variance of Pr, Pg, Pb) andconsequently the variance in the visible (Y), fluorescence (X), andexcitation (Z) image signals (through a similar algebraic matrixoperation as discussed above in connection with FIG. 3A). With thevariance calculated, the signal to noise ratios (SNR) of X, Y, and Z canbe determined. Ideally the system is attempting to maximize the SNR ofthe X, Y, and Z signals.

FIG. 3D depicts a method of stabilizing the visible and fluorescenceimages output from the endoscope image sensor. Block 301 depictsreceiving the RGB photocharge from the image sensor. Block 303 depictsinitializing a value for the regularization constant (a) to stabilizethe images output. Block 305 shows calculating {circumflex over(X)}=Q^(L)P. Block 307 depicts assuming that {circumflex over (X)}=X,then calculating the value of α maximizes SNR_(x) and SNR_(y). Block 309illustrates repeating the a calculation until the value of a converges.Then a final X and Y value are output and monitored. Finally in block311 the value of α is replaced. Blocks 305-311 repeat themselvesindefinitely.

FIG. 4 illustrates a method 400 of medical imaging, in accordance withan embodiment of the disclosure. The order in which some or all ofprocess blocks 401-409 appear in method 400 should not be deemedlimiting. Rather, one of ordinary skill in the art having the benefit ofthe present disclosure will understand that some of method 400 may beexecuted in a variety of orders not illustrated, or even in parallel.

Process block 401 shows simultaneously emitting visible light andexcitation light from a distal end of a fiber optic cable of anendoscope. In one embodiment, a wavelength of the excitation light isoutside a wavelength spectrum of the visible light (e.g., the excitationlight has a longer wavelength than the visible light).

Process block 403 illustrates receiving reflected visible light(including the visible light) with an image sensor. In one embodiment, amajority the excitation light is blocked from being absorbed by theimage sensor with a filter. In some embodiments this may be a notchfilter, or any other wavelength selective filtering.

Process block 405 depicts receiving fluorescence light, emitted from aplurality of dye molecules, with the image sensor, and the fluorescencelight is emitted in response to the plurality of dye molecules absorbingthe excitation light. The fluorescence light may have a longerwavelength than the visible or excitation light. The fluorescence lightis received by the image sensor contemporaneously with the reflectedvisible light. The reflected visible light and the fluorescence lightform combined image data in the image sensor simultaneously.

Process block 407 shows separating the combined image data into visibleimage data; the visible image data is commensurate to the reflectedvisible light received by the image sensor.

Process block 409 illustrates separating the combined image data intofluorescence image data; the fluorescence image data is commensurate tothe fluorescence light received by the image sensor. In one embodiment,separating the combined image data into visible image data andfluorescence image data includes separating the combined image data intored image data corresponding to red photocharge absorbed by the imagesensor, green image data corresponding to green photocharge absorbed bythe image sensor, blue image data corresponding to blue photochargeabsorbed by the image sensor, and florescence image data correspondingto fluorescence photocharge absorbed by the image sensor. In someembodiments, to obtain the red green, blue, and florescence photocharge,a Bayer color filter pattern is used, but the Bayer filter does notblock the florescence spectrum.

Although depicted elsewhere, in come embodiments a composite image maybe formed with the visible image data and the fluorescence image data.The visible image data and the fluorescence image data may be displayedsimultaneously to produce the composite image. This allows for a doctorto clearly identify different areas of the body during an operation. Thecomposite image may include a visible image (including the visible imagedata) and a fluorescence image (including the fluorescence image data).The fluorescence image is overlaid on the visible image. For example ifa tumor is florescent but the surrounding tissue is not, the doctor canmore easily remove the tumor.

The above description of illustrated embodiments of the invention,including what is described in the Abstract, is not intended to beexhaustive or to limit the invention to the precise forms disclosed.While specific embodiments of, and examples for, the invention aredescribed herein for illustrative purposes, various modifications arepossible within the scope of the invention, as those skilled in therelevant art will recognize.

These modifications can be made to the invention in light of the abovedetailed description. The terms used in the following claims should notbe construed to limit the invention to the specific embodimentsdisclosed in the specification. Rather, the scope of the invention is tobe determined entirely by the following claims, which are to beconstrued in accordance with established doctrines of claiminterpretation.

What is claimed is:
 1. An endoscope apparatus, comprising: a fiber opticcable with a proximal end and a distal end opposite the proximal end; alight source optically coupled to the proximal end of the fiber opticcable to emit visible light and excitation light into the fiber opticcable for output from the distal end, wherein the light source isconfigured to emit both the visible light and the excitation lightsimultaneously, and wherein a wavelength of the excitation light isoutside a wavelength spectrum of the visible light; an image sensorcoupled to the fiber optic cable to receive a reflection of the visiblelights as reflected visible light and fluorescence lightcontemporaneously with the reflected visible light; and a processorcoupled to the image sensor to receive combined image data from theimage sensor, wherein the combined image data is representative of thereflected visible light and the fluorescence light and wherein theprocessor includes logic that when executed by the processor causes theprocessor to perform operations including: separating the combined imagedata into visible image data including red image data corresponding tored photocharge, green image data corresponding to green photocharge,blue image data corresponding to blue photocharge; and separating thecombined image data into florescence image data corresponding tofluorescence photocharge.
 2. The endoscope apparatus of claim 1, furthercomprising a filter disposed over the image sensor, wherein the filterblocks a majority of the excitation light from reaching the imagesensor, while passing a majority of the reflected visible light to theimage sensor.
 3. The endoscope apparatus of claim 2, wherein one or morelaser sources emit the visible light and the excitation light, andwherein the wavelength of the excitation light is longer than thewavelength spectrum of the visible light.
 4. The endoscope apparatus ofclaim 3, wherein color filters on the image sensor are configured topass the fluorescence light contemporaneously with the reflected visiblelight to the image sensor, and wherein the fluorescence light has alonger wavelength than the excitation light and is generated in responseto the light source emitting the excitation light.
 5. The endoscopeapparatus of claim 4, wherein the excitation light includes 805 nmlight, and the fluorescence light includes 830 nm light.
 6. Theendoscope apparatus of claim 1, wherein the processor further includeslogic that when executed by the processor causes the processor toperform operations including: forming a composite image with the redimage data, the green image data, the blue image data.
 7. A method ofmedical imaging comprising: simultaneously emitting visible light andexcitation light from a distal end of a fiber optic cable of anendoscope, wherein a wavelength of the excitation light is outside awavelength spectrum of the visible light; receiving reflected visiblelight including the visible light with an image sensor; receivingfluorescence light, emitted from a plurality of dye molecules, with theimage sensor, wherein the fluorescence light is emitted in response tothe plurality of dye molecules absorbing the excitation light, andwherein the fluorescence light is received by the image sensorcontemporaneously with the reflected visible light, and wherein thereflected visible light and the fluorescence light form combined imagedata in the image sensor; separating the combined image data intovisible image data, including red image data corresponding to redphotocharge, green image data corresponding to green photocharge, blueimage data corresponding to blue photocharge; and separating thecombined image data into fluorescence image data corresponding tofluorescence photocharge.
 8. The method of claim 7, further comprisingblocking a majority of the excitation light from being absorbed by theimage sensor with a filter.
 9. The method of claim 7, further comprisingforming a composite image with the visible image data and thefluorescence image data, wherein the visible image data and thefluorescence image data are displayed simultaneously to produce thecomposite image.
 10. The method of claim 9, wherein the composite imageincludes a visible image including the visible image data and afluorescence image including the fluorescence image data, wherein thefluorescence image is overlaid on the visible image.
 11. The method ofclaim 7, wherein the wavelength of the excitation light is longer thanthe wavelength spectrum of the visible light, and wherein a wavelengthof the fluorescence light is longer than the wavelength of theexcitation light.
 12. The method of claim 7, further comprisinggenerating the visible light and the excitation light at a proximal endof the fiber optic cable, opposite the distal end of the fiber opticcable, with one or more laser sources, and wherein the visible light andthe excitation light are emitted from the distal end.
 13. A system formedical imaging, comprising: a fiber optic cable with a distal end and aproximal end opposite the distal end; a light source optically coupledto the proximal end of the fiber optic cable to emit visible light andexcitation light into the fiber optic cable for output from the distalend; an image sensor coupled to the distal end of the fiber optic cableto receive reflected visible light and fluorescence light; and aprocessor disposed in the system and electrically coupled to the lightsource and the image sensor, wherein the processor includes logic thatwhen executed by the processor causes the processor to performoperations including: instructing the light source to emit both thevisible light and the excitation light simultaneously, wherein awavelength of the excitation light is outside a wavelength spectrum ofthe visible light; and receiving combined image data from the imagesensor and separating the combined image data into visible image dataand fluorescence image data, wherein separating the combined image dataincludes separating the combined image data into red image datacorresponding to red photocharge, green image data corresponding togreen photocharge, blue image data corresponding to blue photocharge,and florescence image data corresponding to fluorescence photocharge,wherein the red image data, the green image data, and the blue imagedata are part of the visible image data.
 14. The system of claim 13,wherein the processor further includes logic that when executed by theprocessor causes the processor to perform operations including:controlling one or more laser sources in the light source tosimultaneously emit the visible light and the excitation light; andadjusting a power supplied to the one or more laser sources toindependently control an intensity of the visible light and theexcitation light.
 15. The system of claim 13, further comprising anoptical filter disposed between the image sensor and the reflectedvisible light, wherein the optical filter is a notch filter and blocks amajority of the excitation light from being absorbed by the imagesensor.
 16. The system of claim 13, wherein the processor furtherincludes logic that when executed by the processor causes the processorto perform operations including: forming a composite image with the redimage data, the green image data, the blue image data, and thefluorescence image data, wherein the composite image includes a visibleimage including the visible image data and a fluorescence imageincluding the fluorescence image data, wherein the fluorescence image iscontemporaneously overlaid on the visible image.
 17. The system of claim16, wherein performing a calculation to separate the combined image dataincludes using a red quantum efficiency of the image sensor, a bluequantum efficiency of the image sensor, a green quantum efficiency ofthe image sensor, a florescence quantum efficiency of the image sensor,and a transmission of the excitation light through the notch filter. 18.The endoscope apparatus of claim 1, wherein the processor employsregularized inversion to determine intensity values for the fluorescentimage data and the visible image data.
 19. The method of claim 7,further comprising determining intensity values for the fluorescentimage data and the visible image data using regularized inversion. 20.The system of claim 13, wherein the processor further includes logicthat when executed by the processor causes the processor to performoperations including: determining intensity values for the fluorescentimage data and the visible image data using regularized inversion. 21.The system of claim 20, wherein the red photocharge, the greenphotocharge, the blue photocharge, and the fluorescence photochargeinclude charge generated in pixels of the image sensor in response toreceiving the visible light and the fluorescence light.